Where can I do a long retreat?

I would recommend the Tisarana Buddhist Monastery in Perth, Ontario, for you. It is near Ottawa – the Capital City of Canada. I was there just one month ago. You can take a look into their FB Page too, if you like - as it will give you a better idea.

The monastery is a residence for Buddhist monks and those who wish to train as Buddhist monks. Presently there are 20 monks, and 4 'anagaarika's (trainee monks). It is also a retreat for those interested who may visit for varying periods of time.

Ven. Ajahn Tong Sirimangalo lives at Wat Chomtong. The foundation course is 21 days. That could be a nice start. There are more monasteries with similar style that do 21 day foundation courses like Wat Doi Suthep and Wat Rampoeng. It's possible to stay much longer at Mahasi Sasana Yeiktha Meditation Centre Yangon. I can't find the folder they gave me though, so I don't know the exact conditions.

You can try the Kanduboda Meditation Center which teachers Mahasi Meditation. You have to inquire before hand about the length of your stay.

Also you can try Mitirigala Nissarana Vanaya. Again double check the particular days. This teachers both Mahasi and Pa Auk methods under Most Venerable UdaEriyagama Dhammajiva Maha Thero

Also there are centres in Sri Lanka, Burma, Thai Land and Malaysia which you can try.

Also see: Meditation Centres in Sri Lanka by Andrew Quernmore

Also you might try to use World Buddhist Directory.

Also Goenka Centres does have long retreats if you fulfill some conditions:

10-day Courses for Old Students have the same timetable and discipline as 10-day courses. These courses are open to serious old students who have completed at least three 10-day courses and one Satipaṭṭhāna Sutta course, have not been practising any other meditation techniques since last 10-day course, have been practising this technique of Vipassana for at least one year, are trying to maintain the five precepts in their daily lives, and trying to maintain daily practice.

Special 10-day Courses are open only to serious Old Students committed to this technique who have completed a minimum of five 10-day courses, one Satipatthana Sutta course, given Dhamma Service at least one 10-day course, and have been practicing regularly for at least two years.

Applications must be submitted well in advance as processing may take some time. Students who speak neither English nor one of the other announced course languages may apply for the course, however acceptance into the course will depend on the availability of required course materials, suitable translators and permission of the teacher conducting the course.

20-day Courses are open only to serious Old Students committed to this technique who have completed a minimum of five 10-day courses , one Satipatthana Sutta course, given Dhamma Service at least one 10-day course, and have been practicing regularly for at least two years.

Applications must be submitted well in advance as processing may take some time. Students who speak neither English nor one of the other announced course languages may apply for the course, however acceptance into the course will depend on the availability of required course materials, suitable translators and permission of the teacher conducting the course.

30-day Courses are open only to serious Old Students committed to this technique who have completed a minimum of six 10-day courses (one since their first 20-day course), one 20-day course, one Satipatthana Sutta course, and have been practicing regularly for at least two years.

Applications must be submitted well in advance as processing may take some time. Students who speak neither English nor one of the other announced course languages may apply for the course, however acceptance into the course will depend on the availability of required course materials, suitable translators and permission of the teacher conducting the course.

45-day Courses are open only to persons involved in Dhamma Service and Assistant Teachers who have completed a minimum of seven 10-day courses (one since their first 30-day course), two 30-day courses, one Satipatthana Sutta course, and have been practicing regularly for at least three years.

Applications must be submitted well in advance as processing may take some time. Students who speak neither English nor one of the other announced course languages may apply for the course, however acceptance into the course will depend on the availability of required course materials, suitable translators and permission of the teacher conducting the course.

60-day Courses are open only to active Teachers and Assistant teachers who have completed two 45 Day courses and conduct at least 4 courses annually.

Applications must be submitted well in advance as processing may take some time. Students who speak neither English nor one of the other announced course languages may apply for the course, however acceptance into the course will depend on the availability of required course materials, suitable translators and permission of the teacher conducting the course.

Satipatthana Sutta Courses have the same timetable and discipline as 10-day courses. The difference is that in the taped evening discourses the Satipatthana Sutta is carefully examined. This is the principal text in which the technique of Vipassana is systematically explained. These courses are open to serious old students who have sat (not including courses served) at least three 10-day courses, have not been practising any other meditation techniques since last 10-day course, have been practising this technique of Vipassana for at least one year, and who are trying to maintain their meditation practice and the five precepts in their daily lives, at the very minimum from the time of applying to the course.

Old Student Short Courses (1-3 days) are for any student who has completed the 10-day course with S.N. Goenka and his assistant teachers. All old students are welcome to apply to attend these courses, including those where it has been some time since their last course.

Source: https://www.dhamma.org/en/schedules/schtapovana

http://www.watmetta.org/ Ajan Geoff is the teacher he. He is very knowledge about Buddhism in general, however is trained as a monk of the Thai Forest Tradition.

The list given by Suminda Sirinath S. Dharmasena is quite exhaustive. I will just add that if you never did a long retreat before, you should probably first start by a 10 days retreat.

I already did small retreat of 3 days of zazen in Japan, but I found the 10 days retreat of Goenka to be really hard and just couldn't imagine doing it for 20 days while I was there, it's a big jump. I will certainly do a few more 10 days retreat and will look forward doing 20 days in a row when I will feel ready.

Short answer: It is up to you, but I really suggest you test yourself on 10 days (goenka or not) if you have no prior experience. Because if you were to fail during a longer retreat you will face the risk to be disgusted by meditation or blame yourself while you just gave yourself a too big of challenge.

These courses are the best imo, held in Hamilton, ON Canada, on an individual, on-going basis, free of charge, including room and board for the duration of the course dependent on keeping the eight Buddhist precepts for meditators

Foundation Course – 21 days (approx.)

...Foundation Course in Satipatthana Vipassana Meditation as their first course. Meditation techniques include mindful prostration, one- to six-step walking meditation, sitting meditation based on the rising and falling of the abdomen, the sitting posture, points of bodily contact, as well as contemplation of daily activities from morning to night.

The emphasis in this course is on learning the basic technique of recognition (sati – a.k.a. mindfulness) of the body, feelings, mind, and dhammas (meditation objects) in the present moment. The course follows, as its technical outline, the sixteen stages of insight knowledge found in primary Buddhist texts and commentaries; no formal instruction in the stages of knowledge, however, is given in the foundation course and not all meditators will obtain the same results from the course.

Course content includes daily interviews with a teacher and regular group lectures. No previous experience is required, but advanced meditators in other meditation techniques may request a streamlined course to suit their needs.

They also offer advandanced courses to people who have completed the foundation course or the online course, so one could theoretically streamline several courses https://www.sirimangalo.org/courses/#med